Duntech vs Dunlavy?

I would say that the bass in the Dunlavys might be a just a little faster or tighter (the Duntechs need a lot of power and current to control their woofers, otherwise they can sound muddy in that range), and the highs might be just a little more extended, but all in all I think it's a sideways move, not necessarily a step up. The Sovereigns are a classic design, use better quality parts, and still hold their own even now if you want to hear the music rather than the recording. Plus I believe they have factory service still available (my old Princesses needed replacement drivers at one point, they had the exact spare pair matched for my speaker (we're talking the serial number here, not just the model) in stock). If you want to use a tube amp, though, I think the Dunlavys are better with tubes, the Sovereigns are better with solid state. The Sovereigns need a lot of power to truly come alive, more than the Dunlavys, but when they do there are few speakers that can match them, IMHO.

the sovereigns are still regarded as reference loudspeakers...period. they have also become incredibly rare since the owners won't part with them.

Rcprince, at least until one year ago Duntech gave support to the old Sovereigns, and also they tell to me that this model is still in production and in a very competitive price.
My Sovereigns are biamped with a digital amp (Yamaha MX-D1) for the bass and a tube amp for highs (ASL Hurricane). His sound is really good but as I never heard a big Dunlavy (very rare in Europe) and I always ask to me if they will sound noticeably better.
Recently I bought a pair of crossovers, from a younger Sovereign than mine (but with the same drivers), and I'm working to put better components as Mundorf caps and resistors... I hope that this upgrade will give a more open and detailed sound to this good speakers.